1 /*
2 * Copyright (c) 2013, 2015, Red Hat, Inc. and/or its affiliates.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "memory/allocation.hpp"
25 #include "gc/shenandoah/brooksPointer.hpp"
26 #include "gc/shenandoah/shenandoahConnectionMatrix.hpp"
27 #include "gc/shenandoah/shenandoahHeap.hpp"
28 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
29 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
30 #include "gc/shared/space.inline.hpp"
31 #include "memory/universe.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "runtime/mutexLocker.hpp"
34 #include "runtime/os.hpp"
35 #include "runtime/safepoint.hpp"
36
37 Monitor ShenandoahHeapRegion::_mem_protect_lock(Mutex::special, "ShenandoahMemProtect_lock", true, Monitor::_safepoint_check_never);
38 size_t ShenandoahHeapRegion::RegionSizeShift = 0;
39 size_t ShenandoahHeapRegion::RegionSizeBytes = 0;
40
41 ShenandoahHeapRegion::ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start,
42 size_t regionSizeWords, size_t index) :
43 #ifdef ASSERT
44 _mem_protection_level(0),
45 #endif
46 _heap(heap),
47 _region_number(index),
48 _live_data(0),
49 reserved(MemRegion(start, regionSizeWords)),
50 _humongous_start(false),
51 _humongous_continuation(false),
52 _recycled(true),
53 _root(false),
54 _new_top(NULL),
55 _critical_pins(0) {
56
57 ContiguousSpace::initialize(reserved, true, false);
58 }
59
60 size_t ShenandoahHeapRegion::region_number() const {
61 return _region_number;
62 }
63
64 bool ShenandoahHeapRegion::rollback_allocation(uint size) {
65 set_top(top() - size);
66 return true;
67 }
68
69 void ShenandoahHeapRegion::clear_live_data() {
70 assert(Thread::current()->is_VM_thread(), "by VM thread");
71 _live_data = 0;
72 }
73
74 void ShenandoahHeapRegion::set_recently_allocated(bool value) {
75 _recycled = value;
76 }
77
78 bool ShenandoahHeapRegion::is_recently_allocated() const {
79 return _recycled && used() > 0;
80 }
81
82 void ShenandoahHeapRegion::set_live_data(size_t s) {
83 assert(Thread::current()->is_VM_thread(), "by VM thread");
84 _live_data = (jint) (s / HeapWordSize);
85 }
86
87 size_t ShenandoahHeapRegion::get_live_data_words() const {
88 return (size_t)OrderAccess::load_acquire((volatile jint*)&_live_data);
89 }
90
91 size_t ShenandoahHeapRegion::get_live_data_bytes() const {
92 return get_live_data_words() * HeapWordSize;
93 }
94
95 bool ShenandoahHeapRegion::has_live() const {
96 return get_live_data_words() != 0;
97 }
98
99 size_t ShenandoahHeapRegion::garbage() const {
100 assert(used() >= get_live_data_bytes() || is_humongous(), "Live Data must be a subset of used() live: "SIZE_FORMAT" used: "SIZE_FORMAT,
101 get_live_data_bytes(), used());
102 size_t result = used() - get_live_data_bytes();
103 return result;
104 }
105
106 bool ShenandoahHeapRegion::in_collection_set() const {
107 return _heap->region_in_collection_set(_region_number);
108 }
109
110 void ShenandoahHeapRegion::set_in_collection_set(bool b) {
111 assert(! (is_humongous() && b), "never ever enter a humongous region into the collection set");
112
113 _heap->set_region_in_collection_set(_region_number, b);
114
115 #ifdef ASSERT
116 if (ShenandoahVerifyWritesToFromSpace || ShenandoahVerifyReadsToFromSpace) {
117 if (b) {
118 memProtectionOn();
119 assert(_mem_protection_level == 0, "need to be protected here");
120 } else {
121 assert(_mem_protection_level == 0, "need to be protected here");
122 memProtectionOff();
123 }
124 }
125 #endif
126 }
127
128 #include <sys/mman.h>
129
130 #ifdef ASSERT
131
132 void ShenandoahHeapRegion::memProtectionOn() {
133 /*
134 log_develop_trace(gc)("Protect memory on region level: "INT32_FORMAT, _mem_protection_level);
135 print(tty);
136 */
137 MutexLockerEx ml(&_mem_protect_lock, true);
138 assert(_mem_protection_level >= 1, "invariant");
139
140 if (--_mem_protection_level == 0) {
141 if (ShenandoahVerifyWritesToFromSpace) {
142 assert(! ShenandoahVerifyReadsToFromSpace, "can't verify from-space reads when verifying from-space writes");
143 os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_READ);
144 } else {
145 assert(ShenandoahVerifyReadsToFromSpace, "need to be verifying reads here");
146 os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_NONE);
147 }
148 }
149 }
150
151 void ShenandoahHeapRegion::memProtectionOff() {
152 /*
153 tty->print_cr("unprotect memory on region level: "INT32_FORMAT, _mem_protection_level);
154 print(tty);
155 */
156 MutexLockerEx ml(&_mem_protect_lock, true);
157 assert(_mem_protection_level >= 0, "invariant");
158 if (_mem_protection_level++ == 0) {
159 os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_RW);
160 }
161 }
162
163 #endif
164
165 void ShenandoahHeapRegion::print_on(outputStream* st) const {
166 st->print("ShenandoahHeapRegion: "PTR_FORMAT"/"SIZE_FORMAT, p2i(this), _region_number);
167
168 if (in_collection_set())
169 st->print("C");
170 if (is_humongous_start()) {
171 st->print("H");
172 }
173 if (is_humongous_continuation()) {
174 st->print("h");
175 }
176 //else
177 st->print(" ");
178
179 st->print_cr("live = "SIZE_FORMAT" garbage = "SIZE_FORMAT" bottom = "PTR_FORMAT" end = "PTR_FORMAT" top = "PTR_FORMAT,
180 get_live_data_bytes(), garbage(), p2i(bottom()), p2i(end()), p2i(top()));
181 }
182
183
184 void ShenandoahHeapRegion::object_iterate_interruptible(ObjectClosure* blk, bool allow_cancel) {
185 HeapWord* p = bottom() + BrooksPointer::word_size();
186 while (p < top() && !(allow_cancel && _heap->cancelled_concgc())) {
187 blk->do_object(oop(p));
188 #ifdef ASSERT
189 if (ShenandoahVerifyReadsToFromSpace) {
190 memProtectionOff();
191 p += oop(p)->size() + BrooksPointer::word_size();
192 memProtectionOn();
193 } else {
194 p += oop(p)->size() + BrooksPointer::word_size();
195 }
196 #else
197 p += oop(p)->size() + BrooksPointer::word_size();
198 #endif
199 }
200 }
201
202 HeapWord* ShenandoahHeapRegion::object_iterate_careful(ObjectClosureCareful* blk) {
203 HeapWord * limit = concurrent_iteration_safe_limit();
204 assert(limit <= top(), "sanity check");
205 for (HeapWord* p = bottom() + BrooksPointer::word_size(); p < limit;) {
206 size_t size = blk->do_object_careful(oop(p));
207 if (size == 0) {
208 return p; // failed at p
209 } else {
210 p += size + BrooksPointer::word_size();
211 }
212 }
213 return NULL; // all done
214 }
215
216 void ShenandoahHeapRegion::oop_iterate(ExtendedOopClosure* blk) {
217 if (is_empty()) return;
218 HeapWord* obj_addr = bottom() + BrooksPointer::word_size();
219 HeapWord* t = top();
220 // Could call objects iterate, but this is easier.
221 while (obj_addr < t) {
222 oop obj = oop(obj_addr);
223 obj_addr += obj->oop_iterate_size(blk) + BrooksPointer::word_size();
224 }
225 }
226
227 void ShenandoahHeapRegion::fill_region() {
228 ShenandoahHeap* sh = (ShenandoahHeap*) Universe::heap();
229
230 if (free() > (BrooksPointer::word_size() + CollectedHeap::min_fill_size())) {
231 HeapWord* filler = allocate(BrooksPointer::word_size());
232 HeapWord* obj = allocate(end() - top());
233 sh->fill_with_object(obj, end() - obj);
234 BrooksPointer::initialize(oop(obj));
235 }
236 }
237
238 void ShenandoahHeapRegion::set_humongous_start(bool start) {
239 _humongous_start = start;
240 }
241
242 void ShenandoahHeapRegion::set_humongous_continuation(bool continuation) {
243 _humongous_continuation = continuation;
244 }
245
246 bool ShenandoahHeapRegion::is_humongous() const {
247 return _humongous_start || _humongous_continuation;
248 }
249
250 bool ShenandoahHeapRegion::is_humongous_start() const {
251 return _humongous_start;
252 }
253
254 bool ShenandoahHeapRegion::is_humongous_continuation() const {
255 return _humongous_continuation;
256 }
257
258 void ShenandoahHeapRegion::recycle() {
259 ContiguousSpace::initialize(reserved, true, false);
260 clear_live_data();
261 _humongous_start = false;
262 _humongous_continuation = false;
263 _recycled = true;
264 _root = false;
265 set_in_collection_set(false);
266 // Reset C-TAMS pointer to ensure size-based iteration, everything
267 // in that regions is going to be new objects.
268 _heap->set_complete_top_at_mark_start(bottom(), bottom());
269 // We can only safely reset the C-TAMS pointer if the bitmap is clear for that region.
270 assert(_heap->is_complete_bitmap_clear_range(bottom(), end()), "must be clear");
271 _heap->connection_matrix()->clear_region(region_number());
272 }
273
274 HeapWord* ShenandoahHeapRegion::block_start_const(const void* p) const {
275 assert(MemRegion(bottom(), end()).contains(p),
276 "p ("PTR_FORMAT") not in space ["PTR_FORMAT", "PTR_FORMAT")",
277 p2i(p), p2i(bottom()), p2i(end()));
278 if (p >= top()) {
279 return top();
280 } else {
281 HeapWord* last = bottom() + BrooksPointer::word_size();
282 HeapWord* cur = last;
283 while (cur <= p) {
284 last = cur;
285 cur += oop(cur)->size() + BrooksPointer::word_size();
286 }
287 assert(oop(last)->is_oop(),
288 PTR_FORMAT" should be an object start", p2i(last));
289 return last;
290 }
291 }
292
293 void ShenandoahHeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
294 // Absolute minimums we should not ever break:
295 static const size_t MIN_REGION_SIZE = 256*K;
296 static const size_t MIN_NUM_REGIONS = 10;
297
298 uintx region_size;
299 if (FLAG_IS_DEFAULT(ShenandoahHeapRegionSize)) {
300 if (ShenandoahMinRegionSize > initial_heap_size / MIN_NUM_REGIONS) {
301 err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number "
302 "of regions (" SIZE_FORMAT ") of minimum region size (" SIZE_FORMAT "K).",
303 initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahMinRegionSize/K);
304 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
305 }
306 if (ShenandoahMinRegionSize < MIN_REGION_SIZE) {
307 err_msg message("" SIZE_FORMAT "K should not be lower than minimum region size (" SIZE_FORMAT "K).",
308 ShenandoahMinRegionSize/K, MIN_REGION_SIZE/K);
309 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
310 }
311 if (ShenandoahMinRegionSize < MinTLABSize) {
312 err_msg message("" SIZE_FORMAT "K should not be lower than TLAB size size (" SIZE_FORMAT "K).",
313 ShenandoahMinRegionSize/K, MinTLABSize/K);
314 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
315 }
316 if (ShenandoahMaxRegionSize < MIN_REGION_SIZE) {
317 err_msg message("" SIZE_FORMAT "K should not be lower than min region size (" SIZE_FORMAT "K).",
318 ShenandoahMaxRegionSize/K, MIN_REGION_SIZE/K);
319 vm_exit_during_initialization("Invalid -XX:ShenandoahMaxRegionSize option", message);
320 }
321 if (ShenandoahMinRegionSize > ShenandoahMaxRegionSize) {
322 err_msg message("Minimum (" SIZE_FORMAT "K) should be larger than maximum (" SIZE_FORMAT "K).",
323 ShenandoahMinRegionSize/K, ShenandoahMaxRegionSize/K);
324 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize or -XX:ShenandoahMaxRegionSize", message);
325 }
326 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
327 region_size = MAX2(average_heap_size / ShenandoahTargetNumRegions,
328 ShenandoahMinRegionSize);
329
330 // Now make sure that we don't go over or under our limits.
331 region_size = MAX2(ShenandoahMinRegionSize, region_size);
332 region_size = MIN2(ShenandoahMaxRegionSize, region_size);
333
334 } else {
335 if (ShenandoahHeapRegionSize > initial_heap_size / MIN_NUM_REGIONS) {
336 err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number "
337 "of regions (" SIZE_FORMAT ") of requested size (" SIZE_FORMAT "K).",
338 initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahHeapRegionSize/K);
339 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
340 }
341 if (ShenandoahHeapRegionSize < ShenandoahMinRegionSize) {
342 err_msg message("Heap region size (" SIZE_FORMAT "K) should be larger than min region size (" SIZE_FORMAT "K).",
343 ShenandoahHeapRegionSize/K, ShenandoahMinRegionSize/K);
344 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
345 }
346 if (ShenandoahHeapRegionSize > ShenandoahMaxRegionSize) {
347 err_msg message("Heap region size (" SIZE_FORMAT "K) should be lower than max region size (" SIZE_FORMAT "K).",
348 ShenandoahHeapRegionSize/K, ShenandoahMaxRegionSize/K);
349 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
350 }
351 region_size = ShenandoahHeapRegionSize;
352 }
353
354 // Make sure region size is at least one large page, if enabled.
355 // Otherwise, mem-protecting one region may falsely protect the adjacent
356 // regions too.
357 if (UseLargePages) {
358 region_size = MAX2(region_size, os::large_page_size());
359 }
360
361 int region_size_log = log2_long((jlong) region_size);
362 // Recalculate the region size to make sure it's a power of
363 // 2. This means that region_size is the largest power of 2 that's
364 // <= what we've calculated so far.
365 region_size = ((uintx)1 << region_size_log);
366
367 // Now, set up the globals.
368 guarantee(RegionSizeShift == 0, "we should only set it once");
369 RegionSizeShift = region_size_log;
370
371 guarantee(RegionSizeBytes == 0, "we should only set it once");
372 RegionSizeBytes = (size_t)region_size;
373
374 log_info(gc, heap)("Heap region size: " SIZE_FORMAT "M", RegionSizeBytes / M);
375 log_info(gc, init)("Region size in bytes: "SIZE_FORMAT, RegionSizeBytes);
376 log_info(gc, init)("Region size shift: "SIZE_FORMAT, RegionSizeShift);
377 log_info(gc, init)("Initial number of regions: "SIZE_FORMAT, initial_heap_size / RegionSizeBytes);
378 log_info(gc, init)("Maximum number of regions: "SIZE_FORMAT, max_heap_size / RegionSizeBytes);
379 }
380
381 CompactibleSpace* ShenandoahHeapRegion::next_compaction_space() const {
382 return _heap->next_compaction_region(this);
383 }
384
385 void ShenandoahHeapRegion::prepare_for_compaction(CompactPoint* cp) {
386 scan_and_forward(this, cp);
387 }
388
389 void ShenandoahHeapRegion::adjust_pointers() {
390 // Check first is there is any work to do.
391 if (used() == 0) {
392 return; // Nothing to do.
393 }
394
395 scan_and_adjust_pointers(this);
396 }
397
398 void ShenandoahHeapRegion::compact() {
399 assert(!is_humongous(), "Shouldn't be compacting humongous regions");
400 scan_and_compact(this);
401 }
402
403 void ShenandoahHeapRegion::pin() {
404 assert(! SafepointSynchronize::is_at_safepoint(), "only outside safepoints");
405 assert(_critical_pins >= 0, "sanity");
406 Atomic::inc(&_critical_pins);
407 }
408
409 void ShenandoahHeapRegion::unpin() {
410 assert(! SafepointSynchronize::is_at_safepoint(), "only outside safepoints");
411 Atomic::dec(&_critical_pins);
412 assert(_critical_pins >= 0, "sanity");
413 }
414
415 bool ShenandoahHeapRegion::is_pinned() {
416 jint v = OrderAccess::load_acquire(&_critical_pins);
417 assert(v >= 0, "sanity");
418 return v > 0;
419 }